Some years ago the national CFD project MEGAFLOW was initiated in Germany to combine many of the CFD development activities from DLR, universities and aircraft industry. Its goal was the development and validation of ...Some years ago the national CFD project MEGAFLOW was initiated in Germany to combine many of the CFD development activities from DLR, universities and aircraft industry. Its goal was the development and validation of a dependable and efficient numerical tool for the aerodynamic simulation of complete aircraft which met the requirements of industrial implementations. The MEGAFLOW software system includes the block-structured Navier-Stokes code FLOWer and the unstructured Navier-Stokes code TAU. Both codes have reached a high level of maturity and they are intensively used by DLR and the German aerospace industry in the design process of new aircraft. Recently, the follow-on project MEGADESIGN and MEGAOPT were set up which focus on the development and enhancement of efficient numerical methods for shape design and optimization. This article highlights recent improvements of the software and its capability to predict viscous flows for complex industrial aircraft applications.展开更多
Thermal energy storage(TES)is a key technology for renewable energy utilization and the improvement of the energy efficiency of heat processes.Sectors include industrial process heat and conventional and renewable pow...Thermal energy storage(TES)is a key technology for renewable energy utilization and the improvement of the energy efficiency of heat processes.Sectors include industrial process heat and conventional and renewable power generation.TES systems correct the mismatch between supply and demand of thermal energy.In the medium to high temperature range(100~1000℃),only limited storage technology is commercially available and a strong effort is needed to develop a range of storage technologies which are efficient and economical for the very specific requirements of the different application sectors.At the DLR's Institute of Technical Thermodynamics,the complete spectrum of high temperature storage technologies,from various types of sensible over latent heat to thermochemical heat storages are being developed.Different concepts are proposed depending on the heat transfer fluid(synthetic oil,water/steam,molten salt,air)and the required temperature range.The aim is the development of cost effective,efficient and reliable thermal storage systems.Research focuses on characterization of storage materials,enhancement of internal heat transfer,design of innovative storage concepts and modelling of storage components and systems.Demonstration of the storage technology takes place from laboratory scale to field testing(5 kW^1 MW).The paper gives an overview on DLR's current developments.展开更多
This paper presents a new developed anthropomorphic robot dexterous hand： HIT/DLR Hand II. The hand is composed of an independent palm and five identical modular fingers, and each finger has three degree of freedom ...This paper presents a new developed anthropomorphic robot dexterous hand： HIT/DLR Hand II. The hand is composed of an independent palm and five identical modular fingers, and each finger has three degree of freedom （DOFs） and four joints. All the actuators and electronics are integrated in the finger body and the palm. Owing to using a new actuator, drivers and a novel arrangement, both the length and width of the finger is about two third of its formner version. By using the wire coupling mecha- nism, the distal phalanx transmission ratio is kept exactly 1 ： 1 in the whole movement range. The packing mechanism which is implemented directly in the finger body and palm not only reduces the size of whole hand but also make it more anthropomorphic. Additionally, the new designed force/torque and position sensors are integrated in the hand for increasing muhisensory capability. To evaluate the performances of the finger mechanism, the position and impedance control experiments are conducted.展开更多
Despite significant progress in fuel cell technology,its large-scale industrial application is still challenged by the frequently encountered performance failure during long-term operation.Clarifying the failure mecha...Despite significant progress in fuel cell technology,its large-scale industrial application is still challenged by the frequently encountered performance failure during long-term operation.Clarifying the failure mechanism is the key to extending the lifecycle and enhancing stability.Herein,we have developed a time and space resolved multi-field characterization,including electrochemical impedance spectroscopy,to unveil its underlying mechanism.With this operando and non-destructive characterization,the dynamic evolution of the internal mass transport,heat,and electricity field distribution is fully depicted within an industrial-scale fuel cell in operation.Thus,it is revealed that hydrogen starvation occurs in the outlet region due to the excessive hydrogen consumption during the loading-down process.This can induce local low current density and carbon corrosion,which may subsequently cause severe damage to the structure of the catalyst layer and membrane,ultimately leading to performance failure.With this understanding,we further identify a descriptor for early diagnosis to prevent any potential degradation.The methodology is of significance,which can bring fuel cell technology a step further towards industrial applications.展开更多
A key component of future lunar missions is the concept of in-situ resource utilization(ISRU),which involves the use of local resources to support human missions and reduce dependence on Earth-based supplies.This pape...A key component of future lunar missions is the concept of in-situ resource utilization(ISRU),which involves the use of local resources to support human missions and reduce dependence on Earth-based supplies.This paper investigates the thermal processing capability of lunar regolith without the addition of binders,with a focus on large-scale applications for the construction of lunar habitats and infrastructure.The study used a simulant of lunar regolith found on the Schr?dinger Basin in the South Pole region.This regolith simulant consists of20 wt%basalt and 80 wt%anorthosite.Experiments were conducted using a high power CO_(2)laser to sinter and melt the regolith in a 80 mm diameter laser spot to evaluate the effectiveness of direct large area thermal processing.Results indicated that sintering begins at approximately 1180℃and reaches full melt at temperatures above 1360℃.Sintering experiments with this material revealed the formation of dense samples up to 11 mm thick,while melting experiments successfully produced larger samples by overlapping molten layers and additive manufacturing up to 50 mm thick.The energy efficiency of the sintering and melting processes was compared.The melting process was about 10 times more energy efficient than sintering in terms of material consolidation,demonstrating the promising potential of laser melting technologies of anorthosite-rich regolith for the production of structural elements.展开更多
The global drive for sustainable energy solutions intensified interest in anion exchange membrane water electrolysis(AEMWE),as a promising hydrogen production pathway,leveraging renewable energy sources.However,widesp...The global drive for sustainable energy solutions intensified interest in anion exchange membrane water electrolysis(AEMWE),as a promising hydrogen production pathway,leveraging renewable energy sources.However,widespread adoption is hindered by the high cost and non-optimised design of crucial components,such as porous transport layers(PTL)and flow fields.This study comprehensively investigates the interplay between structure,mechanics,and electrochemical performance of a low-cost knitted wire mesh PTL,focusing on its potential to enhance cell assembly and operation.Electrochemical characterisation was performed on a single 4 cm^(2)cell,using 1M KOH at 60℃.Knitted wire mesh PTL,characterised by approximately 70%porosity,2mm thickness,and 1.098 tortuosity,delivered a 33%improvement in current density compared to the standard cell configuration.Introducing a knitted PTL interlayer reduced cell voltage by 74 mV at 2 A cm^(−2)by improving compression force distribution across the active area,enhancing gas transport and maintaining optimal electrical and thermal conductivity.These findings highlight the significant potential of innovative PTL designs in AEMWE to improve mechanical and operational efficiency without increasing the cost.展开更多
In order to increase the sustainability of future lunar missions,techniques for in-situ resource utilization(ISRU)must be developed.In this context,the local melting of lunar dust(regolith)by laser radiation for the p...In order to increase the sustainability of future lunar missions,techniques for in-situ resource utilization(ISRU)must be developed.In this context,the local melting of lunar dust(regolith)by laser radiation for the production of parts and larger structures was investigated in detail.With different experimental setups in normal and microgravity,laser spots with diameters from 5 mm to 100 mm were realized to melt the regolith simulant EAC-1A and an 80%/20%mixture of TUBS-T and TUBS-M,which are used as a substitute for the actual lunar soil.In the experiments performed,the critical parameters are the size of the laser spot,the velocity of the laser spot on the surface of the powder bed,the gravity and the wettability of the powder bed by the melt.The stability of the melt pool as a function of these parameters was investigated and it was found that the formation of a stable melt pool is determined by gravity for large melt pool sizes in the range of 50 mm and by surface tension for small melt pool sizes in the range of a few mm.展开更多
The development of magnesium batteries strongly relies on the use of a Mg metal anode and its benefits of high volumetric capacity,reduction potential,low cost and improved safety,however,to date,it still lacks suffic...The development of magnesium batteries strongly relies on the use of a Mg metal anode and its benefits of high volumetric capacity,reduction potential,low cost and improved safety,however,to date,it still lacks sufficient cycling stability and reversibility.Along with the electrolyte selection,the interfacial processes can be affected by the anode itself applying electrode engineering strategies.In this study,six different Mg anode approaches–namely bare Mg metal,Mg foil with an organic and inorganic artificial solid electrolyte interphase,Mg alloy,Mg pellet and a tape-casted Mg slurry–are selected to be investigated by means of electrochemical impedance spectroscopy in Mg|Mg and Mg|S cells.While a plating/stripping overpotential asymmetry was observed and assigned to the desolvation during Mg plating,the impedance spectra of stripping and plating hardly differ for all applied anodes.In contrast,the sulfur species significantly influence the impedance response by altering the surface layer composition.By systematic process assignment of the gained spectra in Mg|Mg and Mg|S cells,specific equivalent circuit models for different anodes and cell conditions are derived.Overall,the study aims to give valuable insights into the interfacial processes of Mg anodes to support their further development toward long-lasting Mg batteries.展开更多
Background:Due to its high relevance in sports and rehabilitation,the exploration of interventions to further optimize flexibility becomes paramount.While stretching might be the most common way to enhance range of mo...Background:Due to its high relevance in sports and rehabilitation,the exploration of interventions to further optimize flexibility becomes paramount.While stretching might be the most common way to enhance range of motion,these increases could be optimized by imposing an additional activation of the muscle,such as mechanical vibratory stimulation.While several original articles provide promising findings,contradictory results on flexibility and underlying mechanisms(e.g.,stiffness),reasonable effect size(ES)pooling remains scarce.With this work we systematically reviewed the available literature to explore the possibility of potentiating flexibility,stiffness,and passive torque adaptations by superimposing mechanical vibration stimulation.Methods:A systematic search of 4 databases(Web of Science,MEDLINE,Scopus,and Cochrane Public Library)was conducted until December2023 to identify studies comparing mechanical vibratory interventions with passive controls or the same intervention without vibration(sham)on range of motion and passive muscle stiffness in acute(immediate effects after single session)and chronic conditions(multiple sessions over a period of time).ES pooling was conducted using robust variance estimation via R to account for multiple study outcomes.Potential moderators of effects were analyzed using meta regression.Results:Overall,65 studies(acute:1162 participants,chronic:788 participants)were included.There was moderate certainty of evidence for acute flexibility(ES=0.71,p<0.001)and stiffness(ES=-0.89,p=0.006)effects of mechanical vibration treatments vs.passive controls without meaningful results against the sham condition(flexibility:ES=0.20,p<0.001;stiffness:ES=-0.19,p=0.076).Similarly,moderate certainty of evidence was found for chronic vibration effects on flexibility(control:ES=0.64,p=0.043;sham:ES=0.65,p<0.001).Lack of studies and large outcome heterogeneity prevented ES pooling for underlying mechanisms.Conclusion:Vibration improved flexibility in acute and chronic interventions compared to the stand-alone intervention,which can possibly be attributed to an accumulated mechanical stimulus through vibration.However,studies on biological mechanisms are needed to explain flexibility and stiffness effects in response to specific vibration modalities and timing.展开更多
Concentrated solar power(CSP)plants with thermal energy storage(TES)system are emerging as one kind of the most promising power plants in the future renewable energy system,since they can supply dispatchable and low-c...Concentrated solar power(CSP)plants with thermal energy storage(TES)system are emerging as one kind of the most promising power plants in the future renewable energy system,since they can supply dispatchable and low-cost electricity with abundant but intermittent solar energy.In order to significantly reduce the levelized cost of electricity(LCOE)of the present commercial CSP plants,the next generation CSP technology with higher process temperature and energy efficiency is being developed.The TES system in the next generation CSP plants works with new TES materials at higher temperatures(>565℃)compared to that with the commercial nitrate salt mixtures.This paper reviews recent progressin research and development of the next generation CSP and TES technology.Emphasis is given on theadvanced'TES technology based on molten chloride salt mixtures such as MgCl_(2)/NaCl/KCl which hassimilar thermo-physical properties as the commercial nitrate salt mixtures,higher thermal stability(>800℃),and lower costs(<0.35USD·kg^(-1)).Recent progress in the selection/optimization of chloridesalts,determination of molten chloride salt properties,and corrosion control of construction materials(eg.,alloys)in molten chlorides is reviewed.展开更多
文摘Some years ago the national CFD project MEGAFLOW was initiated in Germany to combine many of the CFD development activities from DLR, universities and aircraft industry. Its goal was the development and validation of a dependable and efficient numerical tool for the aerodynamic simulation of complete aircraft which met the requirements of industrial implementations. The MEGAFLOW software system includes the block-structured Navier-Stokes code FLOWer and the unstructured Navier-Stokes code TAU. Both codes have reached a high level of maturity and they are intensively used by DLR and the German aerospace industry in the design process of new aircraft. Recently, the follow-on project MEGADESIGN and MEGAOPT were set up which focus on the development and enhancement of efficient numerical methods for shape design and optimization. This article highlights recent improvements of the software and its capability to predict viscous flows for complex industrial aircraft applications.
基金funded through the basic DLR funding of the Helmholtz AssociationSpecific support for several projects was given by the German Federal Ministry of Economics and Technology and the German Federal Ministry for the Environment,Nature Conservation and Nuclear SafetyThe CellFlux project is funded by E.ON AG as part of the International Research Initiative.Responsibility for the content of this publication lieswith the authors
文摘Thermal energy storage(TES)is a key technology for renewable energy utilization and the improvement of the energy efficiency of heat processes.Sectors include industrial process heat and conventional and renewable power generation.TES systems correct the mismatch between supply and demand of thermal energy.In the medium to high temperature range(100~1000℃),only limited storage technology is commercially available and a strong effort is needed to develop a range of storage technologies which are efficient and economical for the very specific requirements of the different application sectors.At the DLR's Institute of Technical Thermodynamics,the complete spectrum of high temperature storage technologies,from various types of sensible over latent heat to thermochemical heat storages are being developed.Different concepts are proposed depending on the heat transfer fluid(synthetic oil,water/steam,molten salt,air)and the required temperature range.The aim is the development of cost effective,efficient and reliable thermal storage systems.Research focuses on characterization of storage materials,enhancement of internal heat transfer,design of innovative storage concepts and modelling of storage components and systems.Demonstration of the storage technology takes place from laboratory scale to field testing(5 kW^1 MW).The paper gives an overview on DLR's current developments.
基金supported by the National High Technology Research and Development Programme of China(2006AA04Z255)the 111 Project(B307018)
文摘This paper presents a new developed anthropomorphic robot dexterous hand： HIT/DLR Hand II. The hand is composed of an independent palm and five identical modular fingers, and each finger has three degree of freedom （DOFs） and four joints. All the actuators and electronics are integrated in the finger body and the palm. Owing to using a new actuator, drivers and a novel arrangement, both the length and width of the finger is about two third of its formner version. By using the wire coupling mecha- nism, the distal phalanx transmission ratio is kept exactly 1 ： 1 in the whole movement range. The packing mechanism which is implemented directly in the finger body and palm not only reduces the size of whole hand but also make it more anthropomorphic. Additionally, the new designed force/torque and position sensors are integrated in the hand for increasing muhisensory capability. To evaluate the performances of the finger mechanism, the position and impedance control experiments are conducted.
基金supported by the National Key R&D Program of China[2023YFB4006100]。
文摘Despite significant progress in fuel cell technology,its large-scale industrial application is still challenged by the frequently encountered performance failure during long-term operation.Clarifying the failure mechanism is the key to extending the lifecycle and enhancing stability.Herein,we have developed a time and space resolved multi-field characterization,including electrochemical impedance spectroscopy,to unveil its underlying mechanism.With this operando and non-destructive characterization,the dynamic evolution of the internal mass transport,heat,and electricity field distribution is fully depicted within an industrial-scale fuel cell in operation.Thus,it is revealed that hydrogen starvation occurs in the outlet region due to the excessive hydrogen consumption during the loading-down process.This can induce local low current density and carbon corrosion,which may subsequently cause severe damage to the structure of the catalyst layer and membrane,ultimately leading to performance failure.With this understanding,we further identify a descriptor for early diagnosis to prevent any potential degradation.The methodology is of significance,which can bring fuel cell technology a step further towards industrial applications.
文摘A key component of future lunar missions is the concept of in-situ resource utilization(ISRU),which involves the use of local resources to support human missions and reduce dependence on Earth-based supplies.This paper investigates the thermal processing capability of lunar regolith without the addition of binders,with a focus on large-scale applications for the construction of lunar habitats and infrastructure.The study used a simulant of lunar regolith found on the Schr?dinger Basin in the South Pole region.This regolith simulant consists of20 wt%basalt and 80 wt%anorthosite.Experiments were conducted using a high power CO_(2)laser to sinter and melt the regolith in a 80 mm diameter laser spot to evaluate the effectiveness of direct large area thermal processing.Results indicated that sintering begins at approximately 1180℃and reaches full melt at temperatures above 1360℃.Sintering experiments with this material revealed the formation of dense samples up to 11 mm thick,while melting experiments successfully produced larger samples by overlapping molten layers and additive manufacturing up to 50 mm thick.The energy efficiency of the sintering and melting processes was compared.The melting process was about 10 times more energy efficient than sintering in terms of material consolidation,demonstrating the promising potential of laser melting technologies of anorthosite-rich regolith for the production of structural elements.
基金supported by the European Union and the Clean Hydrogen Joint Undertaking(Grant no.101112055).
文摘The global drive for sustainable energy solutions intensified interest in anion exchange membrane water electrolysis(AEMWE),as a promising hydrogen production pathway,leveraging renewable energy sources.However,widespread adoption is hindered by the high cost and non-optimised design of crucial components,such as porous transport layers(PTL)and flow fields.This study comprehensively investigates the interplay between structure,mechanics,and electrochemical performance of a low-cost knitted wire mesh PTL,focusing on its potential to enhance cell assembly and operation.Electrochemical characterisation was performed on a single 4 cm^(2)cell,using 1M KOH at 60℃.Knitted wire mesh PTL,characterised by approximately 70%porosity,2mm thickness,and 1.098 tortuosity,delivered a 33%improvement in current density compared to the standard cell configuration.Introducing a knitted PTL interlayer reduced cell voltage by 74 mV at 2 A cm^(−2)by improving compression force distribution across the active area,enhancing gas transport and maintaining optimal electrical and thermal conductivity.These findings highlight the significant potential of innovative PTL designs in AEMWE to improve mechanical and operational efficiency without increasing the cost.
基金supported by 40th DLR Parabolic Flight Campaign and within the project"Powder based Additive Manufacturing at reduced Gravitation"(Grant No.FKZ:50WM2068)European Space Agency,OSIP Off-Earth Manufacturing and Construction Campaign(Grant No.4000134280/21/NL/GLC/mk)。
文摘In order to increase the sustainability of future lunar missions,techniques for in-situ resource utilization(ISRU)must be developed.In this context,the local melting of lunar dust(regolith)by laser radiation for the production of parts and larger structures was investigated in detail.With different experimental setups in normal and microgravity,laser spots with diameters from 5 mm to 100 mm were realized to melt the regolith simulant EAC-1A and an 80%/20%mixture of TUBS-T and TUBS-M,which are used as a substitute for the actual lunar soil.In the experiments performed,the critical parameters are the size of the laser spot,the velocity of the laser spot on the surface of the powder bed,the gravity and the wettability of the powder bed by the melt.The stability of the melt pool as a function of these parameters was investigated and it was found that the formation of a stable melt pool is determined by gravity for large melt pool sizes in the range of 50 mm and by surface tension for small melt pool sizes in the range of a few mm.
基金financially supported by the Federal Ministry for Education and Research of Germany(Bundesminis-terium für Bildung und Forschung,BMBF)and the European Commission within the projects“MagSiMal”(03XP0208)“E-MAGIC”(824066),respectively。
文摘The development of magnesium batteries strongly relies on the use of a Mg metal anode and its benefits of high volumetric capacity,reduction potential,low cost and improved safety,however,to date,it still lacks sufficient cycling stability and reversibility.Along with the electrolyte selection,the interfacial processes can be affected by the anode itself applying electrode engineering strategies.In this study,six different Mg anode approaches–namely bare Mg metal,Mg foil with an organic and inorganic artificial solid electrolyte interphase,Mg alloy,Mg pellet and a tape-casted Mg slurry–are selected to be investigated by means of electrochemical impedance spectroscopy in Mg|Mg and Mg|S cells.While a plating/stripping overpotential asymmetry was observed and assigned to the desolvation during Mg plating,the impedance spectra of stripping and plating hardly differ for all applied anodes.In contrast,the sulfur species significantly influence the impedance response by altering the surface layer composition.By systematic process assignment of the gained spectra in Mg|Mg and Mg|S cells,specific equivalent circuit models for different anodes and cell conditions are derived.Overall,the study aims to give valuable insights into the interfacial processes of Mg anodes to support their further development toward long-lasting Mg batteries.
文摘Background:Due to its high relevance in sports and rehabilitation,the exploration of interventions to further optimize flexibility becomes paramount.While stretching might be the most common way to enhance range of motion,these increases could be optimized by imposing an additional activation of the muscle,such as mechanical vibratory stimulation.While several original articles provide promising findings,contradictory results on flexibility and underlying mechanisms(e.g.,stiffness),reasonable effect size(ES)pooling remains scarce.With this work we systematically reviewed the available literature to explore the possibility of potentiating flexibility,stiffness,and passive torque adaptations by superimposing mechanical vibration stimulation.Methods:A systematic search of 4 databases(Web of Science,MEDLINE,Scopus,and Cochrane Public Library)was conducted until December2023 to identify studies comparing mechanical vibratory interventions with passive controls or the same intervention without vibration(sham)on range of motion and passive muscle stiffness in acute(immediate effects after single session)and chronic conditions(multiple sessions over a period of time).ES pooling was conducted using robust variance estimation via R to account for multiple study outcomes.Potential moderators of effects were analyzed using meta regression.Results:Overall,65 studies(acute:1162 participants,chronic:788 participants)were included.There was moderate certainty of evidence for acute flexibility(ES=0.71,p<0.001)and stiffness(ES=-0.89,p=0.006)effects of mechanical vibration treatments vs.passive controls without meaningful results against the sham condition(flexibility:ES=0.20,p<0.001;stiffness:ES=-0.19,p=0.076).Similarly,moderate certainty of evidence was found for chronic vibration effects on flexibility(control:ES=0.64,p=0.043;sham:ES=0.65,p<0.001).Lack of studies and large outcome heterogeneity prevented ES pooling for underlying mechanisms.Conclusion:Vibration improved flexibility in acute and chronic interventions compared to the stand-alone intervention,which can possibly be attributed to an accumulated mechanical stimulus through vibration.However,studies on biological mechanisms are needed to explain flexibility and stiffness effects in response to specific vibration modalities and timing.
文摘Concentrated solar power(CSP)plants with thermal energy storage(TES)system are emerging as one kind of the most promising power plants in the future renewable energy system,since they can supply dispatchable and low-cost electricity with abundant but intermittent solar energy.In order to significantly reduce the levelized cost of electricity(LCOE)of the present commercial CSP plants,the next generation CSP technology with higher process temperature and energy efficiency is being developed.The TES system in the next generation CSP plants works with new TES materials at higher temperatures(>565℃)compared to that with the commercial nitrate salt mixtures.This paper reviews recent progressin research and development of the next generation CSP and TES technology.Emphasis is given on theadvanced'TES technology based on molten chloride salt mixtures such as MgCl_(2)/NaCl/KCl which hassimilar thermo-physical properties as the commercial nitrate salt mixtures,higher thermal stability(>800℃),and lower costs(<0.35USD·kg^(-1)).Recent progress in the selection/optimization of chloridesalts,determination of molten chloride salt properties,and corrosion control of construction materials(eg.,alloys)in molten chlorides is reviewed.
